Ever since I was little, I've been interested in thunder and lightning. The lightning would always crack across the sky and that would be followed by a boom of thunder. When i was young, I neve knew why these things happened or anything about sound and light. But now as a student of physics, I know some interesting facts about these occurances.
Light and sound are both a very big part of our everday life. Without them, life would be very different. Light travels faster than sound. That's why you experience lightning before thunder. Light can travel at about 299792458 meters per second. While sound travels at about 340.29 meters per second. This difference in speed is huge. There is supposedly nothing that can travel faster than light.
If you put a lamp in a vacumn, you'd still be able to see the light it produces. If you put your iPod in a vacumn and played your favorite song, no sound would be produced. This is because sound cannot travel through a vacumn, but light can.
To this day I'm still intrigued by thunder and lightning, but knowing the science behind them is pretty cool too.
Music is such a big part of my life. I honestly cannot imagine what life would be like without it. Suprisingly, I guess I have physics to thank for the music that makes life so great. Without waves, more specifically sound waves, we wouldn't be able to hear music. Or really any sounds.
Sound waves are longitudinal waves. In a longitudinal wave, the medium is moving in parallel of the direction that the wave is going. They're also mechanical wave. That just means that they require a medium to travel through. For example, sound cannot travel in space.
When there are sounds around you, the waves travel into your ears. They vibrate your eardrum which then causes bones in your ear to vibrate. The sound waves are eventually converted into electrical nerve impulses which get sent to your brain. Once registered by your brain, you are able to recognize your favorite song playing.
My neice, Emma, is only a couple months old, but she already has a lot of stuff. Clothes, toys, books, even a little blue wagon for when she gets older.
Probably in five plus years she'll want to drag that thing around all summer. But I'm not so sure how easy it would be for her to do that. How much work would she have to put into that action?
Well to figure out work, you can do W=Fd, W=mgd, or W=Fcos(-)d. I'd probably use W=mgd so I don't have to measure angles or anything. Let's say the wagon is 10 kg, and Emma pulls it 10 meters. Obviously by the time she is 5, gravity won't have changed so that's 9.81 m/s^2. When you plug in to the equation, you get W=(10 kg)(9.81m/s^2)(10 m). You'll end up with 981 J. That seems like a lot of work for a little girl.
You know when you're in the bathroom and you're running the blow dryer, the space heater because it's winter, and then you decide to plug in your phone to charge? And then all of a sudden everything will shut off and make you really angry?
Well, all the power/electricity they were using in the bathroom caused the ciruit to blow. Then you'll end up having to go in the basement and reset the fuse box. Each room in your house has some sort of circuit setup for the electricity to run through. And each circuit can only contain so much until the wires overheat. This can be very dangerous, so as a safety precaution, if the wires are close to overheating they'll shut off to prevent a fire. Next time, try not to have everything plugged in at once!
Newton's first law can also be called the law of inertia. It pretty much means that unless there is an unbalanced force on an object, it will continue doing what is doing whether that be moving or staying still. This law is difficult to see on Earth because we have this stupid thing called friction so things that are moving will eventually stop. Inertia is an objects tendency to resist a change in velocity.
Let's say my dog Cujo (who seems to be the subject of a lot of my blog posts) was 25 kg and running at a speed of 4 m/s on Tuesday, but on Friday he was 26 kg and running at a speed of 4 m/s. Did his inertia change? Yes it did! Another word for inertia is mass. So when he went from 25 kg to 26 kg, his inertia changed too.
You know how in the movie Carrie, they pour paint on her when she gets on stage to recieve her crown? Well how do they time this correctly? I guess they had to use physics to find out how long it would take the paint to hit the girl. Mind you that the original movie was way better than the most recent remake...but we'll ignore that for now!
So anyway, let's say that Carrie was 4 meters below the rig above the stage, all they would have to do is solve for the time to see how long it would take the paint to drop on her. By using a form of the kinematics equation d=(vi)(t)+1/2(a)(t)^2, you can solve for the time by plugging in your units. You end up with a time of .9 seconds. It would only take the paint .9 seconds to hit Carrie and emabrass her in front of everyone in her school.
I think Winter is a great season. It's full of warm clothes, family, and lots of fun seasonal activities. It's also full of freezing temperatures, wet snow, and boots that can't keep your feet dry. While I've never attemped snowboarding or skiing (because of my total lack of coordination) I do enjoy sledding. Yes, it makes me feel 5 again, but I think it's something that you can enjoy at any age.
Ley's say that Jake, a 60 kg boy has just gone down a hill on a sled and has stopped at the bottom. His friend, Talyn who is 40 kg follows him down the hill and runs into him at 8 m/s. Upon the collision of the two sledders, they stick together and move farther across the flat surface at the bottom of the hill. If we wanted to find the speed at which they move together we could start by making a momentum table. This allows us to figure out the momentum of each person before the collision. Since momentum before is the same as momentum after, you would just have to solve for the missing velocity to figure out how fast the two went after colliding.
Playing a game of fetch with my dog is always entertaining. He'll always run after the ball, but he never likes to drop it once he has brought it back. If I wanted to find the speed at which the ball hits the ground once he has dropped it, I can use either kinematics or the formula for energy. Let's say that my dog, Cujo, drops the ball from a height of 3 meters. We would start by setting the potential energy of the ball in his mouth equal to the kinetic energy of the ball once it has hit the ground. It would look like this : (m)(g)(h)=(1/2)(m)(v^2). Since we are trying to solve for speed (v) we would rearrange the formula a little until we got v^2=2gh. If we then plug in the units it would look like this: v^2= (2)(9.81 m/s^2)(3m). You then take the square root of that answer and would get a speed of 7.7 m/s. You could also solve this using kinematics and a Vi,Vf,d,a,t table. You would end up with the same answer and still discover the speed at which Cujo dropped the ball.
I am moving a friend into her new house pretty soon. As many know, moving involves a lot of lifting, carrying objects, and rearranging many times. Work is the process of moving an object by applying a force to it. Let's say that we're trying to move the TV which weights 22 kg onto a TV stand that is 3 meters above the floor. To find the work done on the TV, you would use the formula W=Fd, which can be changed into W=(m)(g)(d). So to solve for work you would plug in your units and it would look like this:
W=(22 kg)(9.81 m/s^2)(3 m).
In the end, 647.46 Joules of work were done on the TV! I just really hope that when I actually help this family move that they don't have more than one TV that is 22 kg!!!
So, I like going to concerts and something that I usually see is crowd surfing. Crowd surfing is definitely a thrill, buts it's interesting how you can find physics in anything; like crowd surfing at your favorite band's concert.
Crowd surfing can be a tricky thing to maneuver. You have to consider mass and some forces like gravity. When you're crowd surfing, you're being held up by the other concertgoers. You have to make sure that they can support you; after all their hands can only hold up so much at a time. This makes me think of free body diagrams. In this case, the object would actually be your body. A force is being applied to you by the people holding you up. The other force at work here is gravity. If the crowd can no longer hold you, and gravity is already pushing you down, then you are falling and hopefully you don't land on your head.
It's usually about this time in high school that everyone is practicing driving and getting their licenses. Physics has an astonishing amount of influence on driving, even if we don't think about it. When you step on the gas, your car is accelerating. And you can measure your velocity when you look at your speedometer measured in MPH.
Something that I think we all fear is the possibility of getting into a car accident. Say you're involved in a head on collision with a car going 70 mph, while you were going 30 mph. The car hitting you would end up pushing your car with more force because it was traveling at a faster speed and therefor had more force behind it. Another factor that can apply to the force of the crash is the mass of the other vehicle. if you're hit by a small car, the damage wouldn't be as bad as if you were hit by a semi-truck.
Halloween is my favorite holiday and I recently threw a Halloween party at my house. But for the safety of my animals, my two cats were to spend their night in the basement. The two didn't really enjoy being lightly tossed into the basement. Now, if you had ever met these cats you would understand why getting them in the basement is tricky; the little buggers are fast!!
Anyways, the force with which they were tossed was definitely not extreme nor was their velocity, so don't get PETA on my case. They proved to be a funny example of projectile motion. they didn't have an initial velocity and I tossed them lightly so they didn't get much height. While they didn't mind being tossed, they didn't like being closed in the basement. They expressed their distaste by literally charging the door. Them attacking the door had not nearly enough force to make any impact, but it's pretty entertaining so see how physics can apply to everyday things.
Just like any other dog, my dog Cujo loves to go for walks. The only problem being that half the time he ends up running after something and I get dragged along for a couple seconds. I never really thought about it before, but Physics can explain a lot of the things that occur when Cujo and I go for our walks.
When we are traveling at a normal pace, I can determine our average velocity by taking our distance and dividing it by how long we have been traveling. But what if Cujo happens to see the neighborhood cat? Of course he's going to take off after it and try to drag me along with him. I can then calculate our average velocity and see that it had increased because we went such a huge distance in a short period of time.
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